1. Field of the Invention
This invention relates to an encrypted mail transmission system.
2. Description of Related Art
Recently, a facsimile apparatus that transmits image data through the Internet according to an operation similar to that of a common facsimile. This type of facsimile is called an Internet facsimile terminal apparatus (hereinafter, “IFAX terminal”), since the Internet is used as a whole or a part of the transmission path.
This type of IFAX terminal converts facsimile data into an electronic mail format to transmit. More specifically, the IFAX terminal converts a read original into MH data, and further converts the MH data into a TIFF file. Further, the TIFF file is converted into a text code, and the data converted into the text code is further converted into data in compliance with the MIME format. Then, the data in compliance with the MIME format is transmitted.
The IFAX terminal is not generally occupied by one person, rather, is shared by plural people in a single department at an office. Further, an electronic mail addressed to the IFAX terminal is automatically received by the IFAX terminal, and is printed out. Thus, the electronic mail might be seen by the people other than the individual specified by the sender. Accordingly, it is considered that the confidentiality of the IFAX terminal is lower than that of a mail reception terminal occupied by a single person, such as a common personal computer.
To improve confidentiality, the IFAX terminal conventionally uses a technology of an electronic signature or data encryption to prevent an interception, rewriting and impersonation of an electronic mail. This type of IFAX terminal is called a “secure IFAX”. A conventional secure IFAX has an IC card reader, reads information (for example, public key, confidential key, and so on) necessary for electronic signature or data encryption from an IC card at a transmission (sender) side, applies an electronic signature process or a data encryption process to an electronic mail by using the information read from the IC card, and then transmits the processed (encrypted) electronic mail. At a receiver side, when an individual designated in the electronic mail inserts his/her own IC card into a slot, the electronic mail is decrypted by using the public key, confidential key, and so on, read from the IC card, and is printed thereafter. Thus, the electronic mail is prevented from being intercepted by a person other than the owner of the IC card.
However, to allow only the owner of the IC card to receive an electronic mail, the conventional secure IFAX logs on a POP server by using a mail account and a password of the owner stored in the IC card, and receives the electronic mail at the secure IFAX of the owner. In this case, the insertion of the IC card into the slot is an indispensable condition of the mail reception. Thus, if periodical accesses to the POP server to receive the latest electronic mail are required, the IC card must be always inserted in the slot. This degrades confidentiality. Thus, it is difficult to maintain the confidentiality of a confidential document, and simultaneously to receive the confidential document as early as possible in real time. Further, when the mail account and the password are stored in the secure IFAX itself to enable a connection to the POP server without the IC card, high level confidentiality cannot be achieved similarly. Accordingly, the conventional secure IFAX cannot achieve two contradictory requirements, i.e., high level confidentiality and immediate (urgent) distribution of a confidential document.